To calculate Robert's score as a percentage, you can use the formula:
\[ \text{Percentage} = \left( \frac{\text{Score}}{\text{Total Points}} \right) \times 100 \]
In this case, Robert's score is 60 and the total points are 80. Plugging in the values:
\[ \text{Percentage} = \left( \frac{60}{80} \right) \times 100 \]
Calculating the fraction:
\[ \frac{60}{80} = 0.75 \]
Now multiply by 100:
\[ 0.75 \times 100 = 75 \]
Therefore, Robert's score as a percentage is 75%.